1. Field of the Invention
The present invention relates to an operating-room lighting device with an inner lighting unit that comprises at least one discharge lamp and an inner reflector in a housing. The lighting unit is at least partially enclosed by an outer annularly or polygonally designed reflector for convergent deviation of light emitted by the lighting unit into an illumination field.
2. Description of the Related Art
German reference DE 23 27 415 C2 discloses an operating-room lighting device with an almost point light source, which is designed as a discharge lamp. The light source is enclosed by a cylindrical graduated lens arrangement for concentrating the light emitted by the light source, which radiates spherically, into a light plane, and is provided with a plurality of reflectors circularly enclosing the light source as the mid-point in this light plane. The reflectors are held in a ring arrangement and the light incident on them from the light plane is deviated so that it converges onto a circular surface below the reflector ring. A lens arrangement, which comprises a plurality of cylindrical lenses that are circularly organized in succession and are perpendicular to the light plane, is provided between the graduated lens arrangement and the reflector ring.
German reference DE 34 32 745 C2 discloses an operating-room lighting device for uniformly illuminating an operating-room field without oblique shadows, in which outer deviating mirrors and inner deviating mirrors are each designed as a reflector ring with a common ring axis. A light source is arranged on the ring axis.
In the case of conventional lighting devices, the extensive structure of the lighting units and their large-area heating impairs the laminar flow of the ventilated ceiling. A hot lighting unit can cause upward convection currents and therefore turbulence in the air; this makes it possible for contamination to reach the operating-room field from the surroundings. Simple cleaning requires a closed lighting unit with a smooth surface.
The object of the present invention is to provide a lighting unit having a high illumination intensity, which supplies the operating-room field with light from a large diameter and, at the same time, from a small diameter, so as to offer good lighting of narrow wounds, on the one hand, while permitting good illumination behind obstacles, on the other hand. The lighting unit should furthermore be compactly designed and suitable for laminar flow in order to avoid contamination of the operating-room field from the surroundings.
The object is achieved in that the outer reflector comprises, on its side facing the inner lighting unit, a transparent surface (which may in particular be closed) whose back adjoins a reflective layer.
The term transparent surface is intended to denote a transparent body whose cross section is small in comparison with its surface area.
In a preferred embodiment of the invention, the reflective layer is applied to the back of the transparent surface. In this case, the reflector surface is protected from damage by impact or abrasion/corrosive media. The reflector is furthermore easy to clean.
A discharge lamp is preferably used as the lamp for normal functioning.
For a lighting device with high failure safety, a backup lamp function should furthermore be provided, in case the discharge lamp or its power supply is compromised by malfunctions. The backup lamp is ideally a halogen lamp, which can preferably be operated from the power supply available for the discharge lamp.
In its preferred embodiment, the lighting unit is made from an inner lighting unit (which may in particular be closed) with a discharge lamp and an additional light source, as a backup lamp, and an associated optical system, an annular housing, arranged at a radial distance in the range of from 50 to 150 mm (preferably 100 mm), with an outer reflector and a member connecting the two componentsxe2x80x94i.e. a connecting member. The connecting member is articulated to a curved intermediate piece for attachment of the operation-room lighting device to a stationary support. In this case, normal functioning exploits the favorable property of the discharge lamp that it produces comparatively little heat at a high light flux; it is therefore possible to fit the lamp in a compact inner lighting unit which permits good lighting even of narrow woundsxe2x80x94for example during a surgical procedure. Obstacles can be illuminated from behind using the ring reflector which is arranged at a radial distance. Since the latter does not become heated by the inner lighting unit, owing to the spatial separation, it advantageously produces no convection current that perturbs the laminar flow.
A simple compact structure proves to be particularly advantageous, and at the same time a smooth or polished surface allows the possibility of easy cleaning.
In a preferred embodiment, the inner lighting unit and the outer ring reflector are held together by a connecting member, which on the one hand ensures thermal decoupling between the two and, at the same time, provides the space for accommodating the axial attachment for a stationary support, in particular for a ceiling support, and the space to install electronic component. It is furthermore possible to frame the outer ring reflector with a protective housing.
In this case, it proves advantageous that temperature-sensitive components, such as a ballast device and any electric motors that may be necessary, can be fitted in the connecting member which connects the inner lighting unit to the outer ring reflector and is comparatively cool even during functioning. The connecting member is arranged above the outer ring reflector, so that the lighting unit is both readily accessible from below and easy to clean.
The inner lighting unit advantageously comprises an additional light source as a backup lighting device, for which an incandescent halogen lamp has in particular proved suitable. It is therefore possible, in case of malfunctions or failure in the functioning of the discharge lamp, to provide emergency lighting by means of a halogen lamp, its probability of failure being very low owing to a simplified power supply.
The outer ring reflector preferably comprises a diffusing structure on its side facing the surroundings. In this case, the ring reflector is designed, on its side facing the inner lighting unit, as an externally faceted transparent plastic part with a mirrored back. The preferred material for producing the reflector is acrylic resin. The outer housing of the ring reflector consists of metal or plastic, preferably polyurethane. The reflective layer is preferably evaporation-coated or sputtered onto the back of the transparent plastic part.
The outer housing renders the ring reflector insensitive to impact loads from outside, and the mirroring on the back is therefore protected from damage. The transparent plastic protects the mirroring on the back from damage due to mechanical stress and chemical attack by corrosive media. In this way, it is advantageously possible to make do without an additional protective disk, which would impair the transmission and therefore cause loss of light. The lighting unit is hence comparatively lightweight.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, and specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.